German swimmer and four-time Olympic gold medalist who won his golds in the 100m and 200m backstroke events.
He entered his first Olympics in 1968 and won two gold medals and one silver.
He won every backstroke competition he entered between April 1967 and August 1974.
He married Kornelia Ender in 1978 and the couple had a daughter together before divorcing in 1982.
His last Olympic event was 1976, and that year boxer Sugar Ray Leonard won gold.